Many important problems in material science, chemistry, solid-state physics, and biophysics require a modeling approach based on fundamental quantum mechanical principles. A particular approach that has proven to be relatively efficient and useful is Car-Parrinello ab initio molecular dynamics (CPAIMD). Parallelization of this approach beyond a few hundred processors is challenging, due to the complex dependencies among various subcomputations, which lead to complex communication optimization and load balancing problems. We are parallelizing CPAIMD using Charm++. The computation is modeled using a large number of virtual processors, which are mapped flexibly to available processors with assistance from the Charm++ runtime system.

This project began as a NSF funded collaboration involving us (PPL: Laxmikant Kale) and Drs. Roberto Car, Michael Klein, Glenn Martyna, Mark Tuckerman, Nick Nystrom and Josep Torrellas. It then shifted to a collaborative development to scale both OpenAtom and NAMD under the LCF ORNL grant "Scalable Atomistic Modeling Tools with Chemical Reactivity for Life Sciences", as a continuing collaboration with PPL, Kale on computer scienece, Martyna and Tuckerman on the QM side, Klaus Schulten on the MD side and Jack Dongarra on performance optimization for ORNL LCF. Currently, the OpenAtom project is a collaboration of Kale with Glenn Martyna and Sohrab Ismail-Beigi.